The present invention relates to cross flow blowers. More specifically, the field of the invention is that of apparatus and methods for cooling motors which drive tangential blowers in air conditioners.
Conventional packaged air conditioners and heat pumps generally include both a conventional centrifugal blower for the indoor heat exchanger and an axial blower for the outdoor heat exchanger. All conventional packaged terminal air conditioners also include some type of dividing wall which divides the indoor portion of the unit from the outdoor portion of the unit. Air is conventionally drawn into the unit through the sides, the rear, the outside, or the bottom of the unit and is blown out of the unit after passing over the heat exchangers.
Air conditioners which have tangential fans for moving air are much more quiet than conventional units because of the lower air velocity through the blowers and optimum spacing between the blower and the cut-off of the air conditioner. Furthermore, the induced air flow through the heat exchanger coils is much more uniform than in conventional units thereby causing substantially full utilization of the indoor and outdoor heat exchanger coils and providing greater efficiency of the appliance.
Further details of a packaged terminal air conditioner are disclosed in copending U.S. patent applications entitled AIR CONDITIONER WITH DUAL CROSS FLOW BLOWERS, Ser. No. 478,342, AIR INTAKE ARRANGEMENT FOR AIR CONDITIONER WITH DUAL CROSS FLOW BLOWERS, Ser. No. 478,416, and DRIVING SYSTEM FOR DUAL TANGENTIAL BLOWERS IN AN AIR CONDITIONER, Ser. No. 478,410, filed on Feb. 12, 1990, and assigned to the assignee of the present invention, which disclosures are incorporated herein by reference.
However, one problem with using tangential cross flow blowers is keeping the motor windings and bearings cool, especially in larger capacity units. The conventional design of a packaged terminal air conditioner having a tangential blower does not provide for ventilation of the motor other than the conventional cooling vents located in the motor housing. High temperatures occurring during operation of the motor can cause motor failure. For centrifugal and propeller type fans, the motor is often placed in the airstream generated by the fan. With tangential blowers, the air flow is perpendicular to the blower's axis of rotation. Some tangential fans have their motor located within the conditioned space behind the air conditioner coil, but this requires additional parts for mounting the motor.
What is needed is an air conditioner which cools the driving motor without sacrificing efficiency and airflow over the heat exchangers.
Also needed is an air conditioner which simplifies the air conditioner design while cooling the driving motor.
Further needed is a method for minimizing the cost and complexity of cooling the driving motor.